1. Field of the Invention
This invention relates to an apparatus and method for geometrically modifying electromagnetic radiation, and more particularly concerns modulation generated by a signaling power supply and a receiver for decoding geometrically modulated signals.
2. Description of the Prior Art
Radio waves are electromagnetic radiation over a defined frequency range. That part of the electromagnetic spectrum used for all forms of communication is commonly referred to as the radio spectrum.
The radio spectrum spans low frequency waves (under 10 kilohertz with a length of several kilometers) to very high frequency waves (300 gigahertz, with a length of around 1 millimeter).
The radio spectrum is considered to be a limited natural resource, and is in many instances overcrowded and subject to interference from a variety of electromagnetic transmitters competing for limited space.
Several transmission systems have been in practical use for many decades, among them continuous-wave unmodulated (CW), and various amplitude modulated (AM) and frequency modulated (FM) transmission systems. More recently developed is the so called "double modulation", or AM with pulse-width modulation
Continuous-wave unmodulated radio signals are those used worldwide by amateur radio enthusiasts and others. This simplest of transmitters consists of a crystal oscillator and a variable frequency oscillator which provide a stable frequency. The power supply drives the oscillator, which emits an unmodulated carrier wave at a selected frequency. This signal may be alternatively connected or disconnected by a standard telegraph key, and sent through an amplifier and antenna. This, in essence, is a Morse-code transmitter.
AM and FM transmitters "modulate" a radio signal or carrier by changing a particular characteristic of the radio signal, either its amplitude by constructive or destructive interference with a lower frequency signal, or its frequency by electronic manipulation.